Messages in this thread | | | Date | Tue, 10 Nov 2009 21:50:07 +0200 | From | Avi Kivity <> | Subject | Re: i686 quirk for AMD Geode |
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On 11/10/2009 08:49 PM, H. Peter Anvin wrote: > >> Why is using KVM doing it right ? It sounds like its doing it slowly, >> and hideously memory inefficiently. You are solving an uninteresting >> general case problem when you just need two tiny fixups (or perhaps 3 if >> you want to fix up early x86-64 prefetch) >> > Why do we only need "two tiny fixups"? Where do we draw the line in > terms of ISA compatibility? One could easily argue that the Right > Thing[TM] is to be able to process any optional instruction -- otherwise > one has a very difficult place to draw a line. > > Consider SSE3, for example. Why should the same concept not apply to > SSE3 instructions as to CMOV? >
Because then user programs would run 20x or more slower than the user expects. Better to terminate early (and teach userspace how to choose the instruction subset correctly).
-- Do not meddle in the internals of kernels, for they are subtle and quick to panic.
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